A small but growing body of research on English and Dutch has found that pronunciation of affixes in a word form is sensitive to paradigmatic probability – i.e., the probability of using that form over other words in the same morphological paradigm. Yet it remains unclear (a) how paradigmatic probability is best measured; (b) whether an increase in paradigmatic probability leads to phonetic enhancement or reduction; and (c) by what mechanism paradigmatic probability can affect pronunciation. The current work examines pronunciation variation of Russian verbal agreement suffixes. I show that there are two distinct patterns of variation, corresponding to two different measures of paradigmatic probability. One measure, pairwise paradigmatic probability, is associated with a pronunciation pattern that resembles phonetic enhancement. The second measure, lexeme paradigmatic probability, can show enhancement effects, but can also yield reduction effects more similar to those of contextual probability. I propose that these two patterns can be explained in an exemplar model of lexical storage. Reduction effects are the consequence of faster retrieval and encoding of an articulatory target, while effects that resemble enhancement result when the pronunciation target of both members of a pair of competing word forms is shifted towards the more frequent of two.